a. Field of the Invention
The present disclosure relates to an accelerometer-based assembly for detecting electrode contact with tissue.
b. Background Art
Electrophysiology catheters are used for an ever-growing number of procedures. For example, catheters have been used for diagnostic, therapeutic, mapping and ablative procedures, to name just a few examples. Typically, a catheter is manipulated through the patient's vasculature and to the intended site, for example, a site within the patient's heart, and carries one or more electrodes, which may be used for mapping, ablation, diagnosis, or other treatments.
Techniques of mapping, visualization and treatment using energizing sources, such as radio frequency (RF) ablation, often rely on the placing of an electrode in consistent mechanical contact with targeted tissue. In particular, lesion formation (such as lesions created by exposure to radio frequency), partially depends upon the adequacy of contact between the electrode and tissue. However, there are some challenges. For endocardial applications, the point of electrode-tissue contact is typically 150 cm away from the point of application of force applied by the operator of the catheter outside of the body. This distance complicates making and maintaining good contact between the electrode and tissue. Moreover, the absolute distance, when coupled with the fact that a beating heart is a dynamically moving wall, gives rise to some functional and theoretical challenges, such as ensuring that the electrode is in constant or near-constant mechanical contact with the myocardial wall, or as needed for effective lesion formation.
Catheter systems having sensor assemblies, such as those mounted on the catheter shaft proximal to the electrode or those mounted remotely in the handle set, leave the possibility, albeit a very small one, of obtaining false positive readings of contact between the electrode and the tissue. Such false positive outcomes may occur, for example, when the catheter wall, and not the electrode, is in contact with the tissue. Such a condition may arise during catheter manipulation in the heart when, for instance, the distal portion of the catheter is curled inwards so much as to lose electrode contact with the tissue, while the distal portion of the catheter is in contact with the tissue. When that happens, remotely placed sensors generate signals due to the deflection of the catheter shaft, thereby falsely indicating contact between the electrode and tissue.
Additionally, current force sensing methods may be sensitive to thermal changes at an electrode, such as during an ablation procedure. This may lead to incorrect readings of electrode interaction with surrounding tissue.
There is thus a need for a system and method that minimizes one or more problems as described above.